I have a Macbook Pro at work and installed the current VirtualBox (3.2.4) today.

However, after using the free VHD image of IE 7 on XP SP3 from Microsoft, the Virtual Operating System (XP) just thought there is no network card provided by the PC (the virtual PC simulated by VirtualBox), even if I set up 4 network cards in Settings, as NAT, host only, etc.

So the XP cannot browse any webpage at all.

Tried VM Fusion (trial version) but it wants .vmdk so can't use .vhd

Parallels (trial version) can import a VirtualBox machine but can't set up a virtual machine using a .vhd file. I don't know how to do it.

Is there any integration package for VirtualBox to make it work and how?

Is VirtualBox providing a "too advanced" network card so XP SP3 doesn't have the driver for it?

For a universal solution you could use disk cloning software within your Virtual PC to dump the disk image in a more universal format. You could then create a new VM in whichever software you prefer and clone the disk image back over from within the new VM.